Spark-plug socket wrench



Oct. 18, 1960 F. B.'PAUL SPARK-PLUG socxm' WRENCH Filed March 14, 1958JZQ/IKZZ 2211/ A ORNEY United States Patent SPARK-PLUG SOCKET WRENCHFrank B. Paul, Flint, Mich., assignor to General Motors Corporation,Detroit, Mich., a corporation of Delaware Filed Mar. 14, 1958, Ser. No.721,517

1 Claim. (Cl. 81-125) This invention relates to spark-plug socketwrenches and more particularly to an insert for a socket wrench to gripand retain a spark plug inserted therein.

In internal combustion engines requiring spark plugs, great difiicultyhas been encountered in installing and removing the spark plugs. Mostengine constructions provide a deep well for the spark plug, making itditficult to properly align the plug on installation. Further, enginesgenerally have the spark plugs projecting upwardly, making it diificultto retain a plug in a wrench on installation, and almost impossible toremove the plug without the plug slipping out of the wrench, resultingin damage to the insulator portion or threaded terminal portion of theplug.

To obviate these difficulties, several types of retainers have been madein the past to be inserted in the socket wrench and protect the sparkplug. These inserts have met with varying degrees of success and havenot completely solved the problems of spark plug installation andremoval.

The device in which this invention is embodied comprises an improvednylon sleeve to be inserted in a standard socket wrench. The sleeveprovides the proper gripping and retaining functions necessary and givesa longlasting tool. The terminal threads and insulator portion of thespark plugs are protected at all times, whether actually installing orremoving the spark plug, or in carrying the spark plug and wrench fromplace to place. Thus, greater ease in installing and removing the plugis obtained and the plugs are well protected, resulting in moreefiicient installations, less operator etlort, and consequent savings intime and money.

In the drawings:

Figure 1 is an elevation of the spark-plug socket wrench and insert withparts broken away and in section and having a spark plug insertedtherein, showing the gripping action given the plug by the insert.

Figure 2 is a cross-sectional view of the wrench and insert of Figure 1,showing the insert in its normal position.

Figure 3 is an isometric view of the wrench insert of Figure 1.

Figure 4 is an end view of the socket wrench and insert, taken in theplane of line 4-4 of Figure 2 and looking in the direction of thearrows.

Referring more particularly to the drawings, Figures 1 and 2 best showthe insert mounted in the spark-plug socket wrench. The socket wrench isa standard twelve-point socket wrench having a wrench body 12 and twelvetriangular projections 13 extending part way up the wrench body. Theprojections terminate in a shoulder 14 which limits the movement of aspark plug into the wrench. A rectangular opening 16 is provided in theupper end of the wrench body for the insertion of a handle, or someother turning means, and has indentations 18 provided therein. Theindentations provide a lock for the handle member inserted in the wrenchopening 16.

A nylon sleeve 20 is received in a central bore 22 of the Wrench body12. The upper half of the insert 24 is of slightly greater outsidediameter than the diameter of the bore such that the insert will beslightly compressed and retain itself in the wrench body. The lower halfof the insert 26 is of less outside diameter than the diameter of thebore, to provide an annular clearance 28 between the insert and the wallof the bore. A plurality of fingers 30 are formed in the lower half 26of the sleeve by cutting four slots 32 half way up the length of theinsert. The fingers therefor comprise the sleeve material between theslots. Also provided on each finger portion of the insert is an inwardlyextending annular projection 34 to grip the insulator portion of a sparkplug inserted therein.

In Figure 1, a standard spark plug, indicated generally by the numeral36, is shown inserted in the spark-plug socket wrench 10 and the sleeve20. The spark plug consists of a threaded terminal post 38, extendingthe length of the plug, an insulator portion 40, surrounding thethreaded terminal post, a nut portion 42, by which the spark plug isthreaded into its place, and a threaded portion 44 which is received inthe engine requiring the spark plug. The nut portion 42 is hexagonal inshape and fits within the triangular projections of the socket wrench sothat the spark plug may be turned.

The insulator portion 40 of the spark plug extends into the nylon sleeve20 and is thus protected from the metal walls of the socket wrench. Theinwardly extending annular projections 34, formed on the lower ends ofthe fingers are of less inside diameter than the outer diameter of theinsulator portion. When the spark plug is inserted in the wrench andsleeve the insulator portion forces the fingers against the side wall ofthe bore taking up the clearance space 28 and retaining the spark plugin the wrench. Holding action for the spark plug is therefore providedby the fingers bending and radially expanding into the clearance space28.

In removing the spark plug from the wrench, or in removing the wrenchfrom an installed spark plug, all that is necessary is a pull in theaxial direction to slide the insulator portion out of the sleeve, thefingers returning to the position illustrated in Figure 2.

I claim:

A spark-plug socket wrench having a plug-receiving bore therein, a nylonsleeve receivable in said bore, one end of said sleeve being of slightlylarger outside diameter than said bore for frictionally retaining saidsleeve in said bore, a plurality of fingers formed in the other end ofsaid sleeve, the outside diameter of said fingers being less than thediameter of said bore, and inwardly extending projections formed on theinside of said fingers for receiving and retaining a spark plug at itsinsulator portion, said fingers bending outwardly within saidsocketwrench bore as a spark plug is inserted therein.

References Cited in the file of this patent 'UNITED STATES PATENTS Re.23,885 Hubbard Oct. 5, 1954 2,294,193 Merrirnan Aug. 25, 1942 2,304,271Mern'man et a1 Dec. 8, 1942 2,752,811 Wenchel July 3, 1956 2,778,664Herbenar Jan. 22, 1957 2,832,245 Burrows Apr. 29, 1958 FOREIGN PATENTS491,141 Italy Feb. 24, 1954

